led blowouts

[hoss]

It's well known that if you severely overdrive an led that it will fail.
In another post the term "expensive firecracker" was used.
Just curious... if I deliberately attempt to "overwhelm" an led with high current is there ever a situation where the led will pop apart?
In other words has anyone here seen an overdriven led physically fly apart to the point where you should be wearing safety glasses or goggles?
My personal opinion is that this could not happen but who am I know for sure - I'm a still a relative newby here.

 

[The_LED_Museum]

I've had them literally blow to pieces. The pieces can be ejected at high enough speeds to warrant the use of protective eyewear. You may also need a can of wizard, a swimmer's noseplug, and an electric fan; as this explosive disintegration tends to leave a rather noxious odor in the vicinity.

Chemically, there is a hazard but it is very small due to the small amounts of material involved. The cloud of "smoke" may contain epoxides, halogens, arsenic and metal arsenides, lead, tin, and several other metallic and transmetallic compounds in addition to complex hydrocarbons liberated from burning resin. The only thing you'll notice is that awful stench; and if you can vent that to atmosphere (outside), and generally avoid inhaling it, there should be nothing to worry about unless you just pop one LED after another, day after day, year after year.

 

[hoss]

Many sincere thanks for that information ...I plan to be VERY carefull from now on.

 

[Willmore]

The higer the current, the more energy involved in the explosion--the more likely more 'energetic' compounds will be released. Also, the chemestry of the LED will matter. I mean, if the element isn't in the LED to start with no amount of energy will bring it into being. (they're not the Sorcerors stone.

So, beware old high-brightness reds with arsenic, but don't worry to much about modern Blues and Greens with artificial Garnet in them.

Most jem stones are practically inert.

I'd be careful with *anything* I hook to a car battery. Especially a car, but also an LED.

 

[Rothrandir]

has anybody ever tried to stick the leads of a led into an outlet??? that might prove interesting...

 

[The_LED_Museum]

All that would likely do is make a "bang" sound, producing ejecta, a cloud of stinky fumes, and a permanent scorch on the outlet cover & melted metal inside the receptacle. Much the same thing you get if you try to plug in a paper clip or a barbie pin.

 

[Doug Meister]

I can see it now. A guy is led off in handcuffs from an air terminal yelling "My LED flashlight is NOT a bomb. I wasnt attemptimg to blow the plane up."

--Ðøug

 

[Daniel Ramsey]

nowadays even the lightest joke can be taken VERY seriously

 

[Saaby]

If I were to blow up a LED in a socket (I have a long life ahead of me--maybe I will some day) it would be in a very scientific matter. I would do it outside using an outlet turned on from a remote location, kinda like setting off a model rocket.

 

[x-ray]

Just tried a little experiment (partly in the name of science & partly because I was bored)

Attached blue LED (from a broken ASP Sapphire) to a 9v battery:

</font><ul type="square">[*]<font size="2" face="Verdana, Arial">Very bright blue light for about 5 seconds </font>[*]<font size="2" face="Verdana, Arial">Light then slowly faded out to nothing </font>[*]<font size="2" face="Verdana, Arial">Now glowing orange (due to heat build up I think) </font>[*]<font size="2" face="Verdana, Arial">Getting brighter </font>[*]<font size="2" face="Verdana, Arial">Wow my LED's turned into an incandescent

</font>[*]<font size="2" face="Verdana, Arial">Finally after about 10 seconds of bright orange light, a puff of smoke, a nasty smell and a dead LED </font>[/list]<font size="2" face="Verdana, Arial">Why is blowing stuff up so much fun

 

[Saaby]

X-Ray...we're all waiting for a write up on blowing up little yellow smileys

 

[x-ray]

Originally posted by Saaby:
X-Ray...we're all waiting for a write up on blowing up little yellow smileys

<font size="2" face="Verdana, Arial">The microwave's all setup, Just got to catch one of the little b******s

 

[Steelwolf]

I'm one of those who have actually blown up an LED too. Was using a lab power supply, set up for current-on-demand, voltage controlled. LED was a white one, partially damaged by AC power in past experiment. Wanted to see how much extra power was needed to get it lit again.

It actually blew up with enough force to blast apart the LED and send fragments of the plastic encasement all across the room. I was left with the leads, the die, a small piece of plastic and an acrid smell (quickly dissipated by the fan). Don't think I ever recovered all the pieces of plastic.

I don't recall how many volts and how much current it was drawing when it popped.

 

[star882]

I once done this by accident.
I was playing with electronics, and made a mistake that connected the LED directly across the power supply.
The power supply was pumping about 5 amps through the LED, causing it to blow in two with a small bang.

 

[Jonathan]

I've never blown up an LED, but I have blown up other semiconductors.

The most memorable occasion was when I was working with some motor control hardware. The main power supply was a three phase, 240V, 40A per leg wall switch, which was rectified to about 300V DC with a some hefty diodes and a capacitor bank.

The circuit had previously been tested with 36V DC, and we were ramping up to full power.

The problem was a small design error on the 'logic' side of the system. There were diodes which were used as part of a 'charge pump' circuit to provide 12V _above_ the floating output of a transistor switching circuit, for gate drive. Basically a small 12V power supply was being used along with some diodes and a capacitor to supply a local 12V which might be referenced to the full 300V output of the main power supply. The problem was that I brain farted and selected diodes based upon the 12V supply, rather than the 300V supply.

When we applied full power, the diodes immediately started conducting, and connected the 300V main supply to the 12V supply. As soon as this happened, all hell broke loose.

Wires ignited. Resistors ignited. All of the ICs on the board went off like firecrackers, _loud_ firecrackers. Magic smoke poured out of my computer (I'd been really cowboy, and used the PC power supply as the 12V supply for the circuit...never again.) The 6 gauge wires which were laying on the floor between the wall switch and the apparatus literally jumped several inches because of the current flow.

The stench of burned resin and silicon hovered in the air for hours. All of the ICs had little craters in the center where the silicon dice had rapidly self dissembled. My boss was a touch disturbed, but luckily the power switch was on the other side of the room, and no-one was hurt.

We've also had a fully charged capacitor bank fail. Energy storage at failure was probably about 10,000WS, possibly higher. Apparently burning aluminium shot out of the enclosure, but for the most part the damage was properly contained. No other components failed during this accident, because we've learned lots about properly isolating failures.

-Jon